Field of the Invention
An embodiment of the present invention relates to a developer container, a developing device, a process cartridge, and an image forming apparatus.
Herein, the developer container is a container that accommodates developer. The developing device is a device including at least a developer carrying member that carries developer. The process cartridge is a cartridge integrally including an image bearing member, such as an electrophotographic photosensitive drum, and a process unit that acts on the image bearing member. Examples of the process unit include a developing means, a charging unit, and a cleaning means. The process cartridge includes at least one of these elements as the process unit. In addition, the process cartridge is detachably attached to the apparatus main body of the image forming apparatus.
The image forming apparatus is an apparatus that forms an image on a recording material. Examples of the image forming apparatus include a copying machine, a printer (e.g., an LED printer and a laser beam printer), a facsimile apparatus, and a word processor.
Description of the Related Art
In electrophotographic image forming apparatuses (hereinafter, referred to as “image forming apparatuses”), as an image bearing member, an electrophotographic photosensitive member generally formed in the shape of a drum (i.e., a photosensitive drum) is evenly electrically charged. Then, the charged photosensitive drum is selectively exposed to light, thereby forming an electrostatic latent image on the photosensitive drum. Then, the electrostatic latent image formed on the photosensitive drum is developed as a toner image by using toner as developer. Thereafter, the toner image formed on the photosensitive drum is transferred onto a recording material such as a recording sheet or a plastic sheet. Further, heat or pressure is applied to the toner image that has been transferred onto the recording material to fix the toner image on the recording material. In this way, image forming apparatuses perform image recording.
In general, toner supply, and maintenance of various kinds of process units are required for such image forming apparatuses. In order to facilitate the toner supply and the maintenance of the process units, a photosensitive drum, a charging means, a developing means, and a cleaning means are integrally formed into a frame as a cartridge. Process cartridges that are attachable to and detachable from an image forming apparatus main body are in practical use.
This process cartridge system, with which users are able to do maintenance of apparatuses by themselves, can provide image forming apparatuses having improved operability and superior usability. Thus, the process cartridge system is widely employed in the field of the image forming apparatuses.
In addition, the developing means included in the aforementioned process cartridge includes a developing roller and a developing blade. The developing roller supplies toner onto the photosensitive drum. The developing blade regulates a toner layer on the developing roller. The developing means is separated into a toner chamber and a developing chamber. The toner chamber accommodates toner. In the developing chamber, the developing roller and the developing blade are arranged. The toner chamber and the developing chamber are in communication with each other via a toner supply opening.
In many cases, a toner supply opening of a new process cartridge is sealed by a toner sealing member. This is to prevent leakage of the toner in the toner chamber during distribution of the process cartridge. The toner sealing member is bonded to the toner supply opening at the periphery of the toner supply opening by heat welding or the like. There is a type of toner sealing member that is unsealed by the user when the process cartridge is used. There is another type of toner sealing member that is automatically unsealed. Japanese Patent Application Laid-Open No. 2014-134708 discusses a configuration in which a toner sealing member is automatically unsealed. According to this configuration, a rotary member in a toner chamber winds and unseals the toner sealing member.
Japanese Patent Application Laid-Open No. 2014-167606 discusses a configuration in which a rotary member that unseals a toner sealing member also serves as a toner conveyance member. According to the configuration, at least one hole is formed in the toner sealing member. This is to prevent increase in the load for pushing away surrounding toner and winding and unsealing the toner sealing member when the toner sealing member is wound and unsealed. The toner is caused to pass through the at least one hole in the toner sealing member, thereby reducing the amount of toner that the toner sealing member has to push away. This reduces the load needed to wind and unseal the toner sealing member.
However, the following problems can arise in a process cartridge having the configuration in which a toner sealing member that is a sheet member is wound and unsealed via an unsealing member and at least one hole is formed in the toner sealing member.
First, if fluidity of the toner is decreased during distribution, a sufficient amount of toner may not pass through the at least one hole, depending on the size of the at least one hole or the number of holes. This may increase the load for moving (i.e., winding and unsealing) the toner sealing member. Thus, it is necessary to set the size of the at least one hole to be large enough so that the toner having lowered fluidity can pass through the at least one hole, or to increase the number of holes. Meanwhile, it is problematic in that, if the size of the at least one hole formed in the toner sealing member is excessively large or if an excessively larger number of holes are formed in the toner sealing member, the strength of the toner sealing member is decreased.